HI Netrapal,
Yes This Can Be Done...First You have to Boot from USB/DVD And then Follows up the installation step...i feel During the Installation Major step is Partitioning Where You have to put a bit calculation...Now You have to give appropriate size for The O.S...and rest of the things will be done by the system...if you still have any problem then post it here......

Ok,
1. Boot from the disc/USB,
2. As your system starts booting up by disc/Usb,, 5 Options will be shown on Display screen like
>>> Try Linux Without Installing.
>>> Install Linux.
>>> check disk for defect.
>>> Test Memory.
ONe more option may come i don`t know what exactly that will be,,,actually that is not imp. one in installation process...
3. now as you wanna install linux click on second option "Install Linux".
4. Now "Welcome Screen" Will be pop up And Choose Your Language And hit Continue..
5. Now for Installing Ubuntu. Your computer will need at least 4.3 GB of free space. You will want more than this if you want to install programs and create files. here
>>>> Check the “Download updates automatically” box, as well as the “Install this third-party software” box. The third-party software will allow you to play MP3 files as well as watch Flash video (such as YouTube)...make sure internet connection is ok..
6. Now select >>> install Linux alongside your previous Windows installation <<<< you will be given the option to choose your operating system each time you reboot your computer. Your Windows files and programs will remain untouched.Now Hit Continue...
Note :- If you replace your installation of Windows with Ubuntu all of your Windows files, documents, and programs will be deleted.Be careful while attempting dis step..
7. Now partition size. As you are installing Ubuntu alongside Windows, you can use the slider to adjust how much space you would like to designate for Ubuntu. Remember that Ubuntu will take up about 4.3 GB when it is installed, so be sure to leave some extra space for programs and files.Now click on Install Now....
8. Now Choose your location...if internet connection is there it will detect automatically...
9. Now choose Keyboard Layout Option...
10. And next Fill Login INfo...And then restarts ...